1. Field of the Invention
The present invention relates to a telephone system that performs switching and processing of telephone information for its transmission and, more particularly, to a telephone communication system that interconnects a plurality of telephone stations via a network and performs switching, control and other forms of processing necessary for the transmission of telephone information between the telephone stations.
2. Description of the Prior Art
For example, because a key telephone system is now in wide use as a conventional telephone communication system and PBX is also widespread as a local telephone system, these convey daily telephone information.
Of these conventional telephone communication systems, the key telephone system is of “a” build-in” type. Therefore, it has been equipped with functions one after another, in a piecemeal fashion, along with the various stages of development of the infrastructure of our society. As a result of this, software has become bloated and the interface configuration has become accordingly complex, making it very difficult to change functions and add new functions. Further, because station states and subscriber data are placed under centralized control by a key service unit, the extension of the system scale is restricted by the ability of the main processor, and hence the system extension is difficult to implement. Besides, the construction of a local extension network by connection principal locations requires a contract for a leased telephone communication line, inevitably raising the operating costs of the system.
In the case of PBX, because its scale is large, the above-mentioned difficulties and defects become even more severe than with the conventional systems.
For the reasons given above, the prior art solutions find it difficult to implement a simple-structured system that both efficiently performs switching, control and other processing functions necessary for the conveyance of telephone information between stations and also can deal with an increase or decrease in the number of stations in the system with a high degree of flexibility.